A suicide car bomb attack on the Iraqi police in south of Baghdad on Thursday killed 25 and wounded another 75, a local police source told Xinhua.

"Our latest reports put the toll from the suicide car bombing in the city of Hillah at 25 and 75 wounded," the source from Hillah police told Xinhua on condition of anonymity.

The attack occurred in the center of Hillah, the capital city of Babil province some 90 km south of Baghdad, when a suicide bomber rammed his explosive-laden car into the entrance of a police headquarters during a shift change as many policemen were gathering outside the building, the source said.

The powerful blast badly damaged the facade of the headquarters and a large part of the building, the source added.

Most of the killed and wounded were policemen and several cars, nearby shops and buildings were damaged in the blast, he said, adding that the police force has cordoned off the area for investigation.

Earlier, a local police source put the toll at 15 killed and 60 wounded.

The attack came as the Iraqi security forces increased security alert in Baghdad and other Iraqi cities as they expected deadly attacks to be carried out by al-Qaida militants in retaliation for the killing of al-Qaida leader Osama bin Laden in Pakistan.

Violence and sporadic high-profile bomb attacks continue in the Iraqi cities despite the dramatic decrease of violence over the last three years.